Roots:The
roots of grasses are fibrous, which makes them good soil binders and the
reason they are planted for erosion control.

Stems:Grass
stems are called culms.These
are usually hollow, except at the nodes.Branches that originate from near ground level are tillers.Many grasses have a rhizome, stolon, etc.

Leaves:Typically alternate and in one plane.The leaf is made of three parts; blade, sheath and ligule.The sheath is usually not fused around the stem, but rather is open.The ligule is a small tissue found between the blade and sheath.It can be hairy, membranous, even absent, and is important
taxonomically.There may also
be auricles present, which are small ear‑like appendages at the
junction of sheath and blade.

Flowers:
Perfect and imperfect (plants usually monoecious, rarely
dioecious).The petals and
sepals are absent, reduced to lodicules.There are 2 - 3 lodiculesper
flower.The function of the
lodicules is to open up the flower (they absorb water and swell pushing
apart the bracts surrounding the flower).

Androecium:
Usually three stamens, these typically dangle out of the
flower at maturity.

Gynoecium:
The pistil has 2, feathery styles.

Pollination:
Grasses are adapted for wind pollination.Adaptations for wind pollination:copious amounts of pollen, plumose stigmas, anthers stick out of the
flower when the flower is mature.

Fruit:Caryopsis or grain, single seeded fruit in which fruit wall and seed
coat are fused and indistinguishable from one another.

Parts of the grain:embryo (germ) - rich in oil/protein; endosperm - rich in starch;
aleurone layer - protein/oil, secretes enzymes to initiate germination; bran
- fruit and seed walls.Polished
grain - removed bran and aleurone.One
advantage is that the grain will not spoil as readily; the disadvantage is
that it removes much of the nutrional value of the grain.

Inflorescence:
The flowers are subtended by modified leaves called
bracts.The outer bract (lemma) may form an extension
called an awn.The palea is the
inner bract. It is generally smaller, oriented toward the main stem axis,
and 2 veined.A flower with
lemma and palea is a floret.

Florets
are arranged in clusters called spikelets.The bottom pair of bracts of a spikelet are sterile (no flower in
axil) and are called glumes.A spikelet may be comprised of from one to many florets.The inflorescence is considered to be an arrangement of spikelets
rather than individual flowers.

IV.Pseudocereals
Plants that bear a superficial resemblance to the true
grasses and/or have seeds that do and are used in similar ways as cereal grains.Examples are Amaranth, quinoa (Chenopodium quinoa) and buckwheat (Fagopyrum
esculentum)

V.Domestication/Selection of cereals

The following is a series of trends in the domestication of
cereals (these were also discussed in our Origin of Agriculture class)

Dwarf
plants - minimize lodging

Unbranched
- more grains per stalk and more synchronous ripening

Synchronization
of ripening

Synchrony
of tiller formation - ease of harvest, maximize yield

Fruit
retention - eliminate shattering

Ease
of threshing and winnowing - threshing is the process of separating the
grain from the bracts (chaff); winnowing is the process of removing freed
grain from the chaff.Traditional methods vs. modern.

Increase
grain size and quality

VI.Maize (Zea mays)

Taxonomy.
Commonly called corn in N. America.However, corn is a generic name for any cereal in some parts of the
world (i.e., Britain).

2.
Ancestors.
The most likely candidate is teosinte, another
grass in the genus, Zea. The
vegetative features of teosinte and corn look very similar.
However, there are a variety of differences including:

Teosinte

Corn

shattering

yes

no

hard case (glume) surround grain

yes

no

number of fertile spikelets per cupule

1

2

number of rows of cupules

2

4 - 10

branching

yes, multiple branches from near base

one main stem

position of tassles & cobs

each side branch ends with a tassel;
cobs produced below the tassels

tassels only on end of main stem,
cobs on side of main stem

3.
Conclusions.
From the table we conclude that the evolution
of corn from teosinte required, at a minimum, the following changes in
teosinte: (a) suppression of lateral (side) branches; (b)
suppression of female cobs on the side branches; (c) conversion of the
terminal male tassels on the side branches to a cob; (d) reduction of
the hard case around the grain; and (e) loss of shattering.

Recent studies by John Doebley and colleagues, Hugh Iltis, and others
have shown that corn and teosinte differ by about five different
genes. This is fewer than originally anticipated and suggests why
corn rapidly appears in the archaeological record.

VII.Wheat (Triticum sp.)

Domestication.Evidence
for wheat as early as 8-7,000 BC; domesticated in Near East

Emmer (Triticum turgidum).
This is a hybrid between einkorn and a wild wheat and
resulted from a doubling of the chromosomes.It has 28 chromosomes (4n).

Durum (Triticum durum).
Probably a mutation that was derived from emmer wheat.The main differences between emmer and durum is that durum wheat is:(a)free threshing; and
(b) good quality protein (gluten).Makes
semolina flour that is used extensively in pastas.Grown in northern US especially ND and Canada.Has 28 chromosomes (tetraploid).

Bread (Hard/Soft, Red or Club; Triticum aestivum).
This is the major wheat in cultivation.It has a high protein content and good gluten.It has 42 chromosomes - is a hexaploid and is a result of a cross
with Aegilops squarrosa.

Hardwheats have a higher protein content, require less rain,
used for breads

Soft
wheats produce a softer flour, require less rainfall, used for
pastries

Spring
wheat - planted in spring, harvested in fall

Winter
wheat - planted in summer, harvested following summer. These
wheats must overwinter in order to flower and produce grains.This required cold treatment is called vernalization.

Wheat
Success.
The success of the wheat crop in the US was dependent
on:

Overcoming
wheat rust (Puccinia graminis) - a fungus that infects the
wheat plant and lowers yields.Wheat rust has two hosts; the other is barberry. It
was thought that the destruction of wild barberry plants growing
near wheat would be a good way to combat this disease - but it
didn't prove too successful;

Introduction
of drought and lodging resistant varieties; and

Development
of flour mills.White
flour - remove bran and germ, less nutritious but better
storage.Whole
wheat - leave bran and germ but spoils more readily.Whole wheat flour is reasonably nutritious.It has a good quality protein, and is just missing vitamin
A, B12, C and iodine (these are usually added backed to
"enriched" flours).Traditionally the grain was parched to remove the bran, but
this ruined the grain and quality of the gluten.

VIII.Rice (Oryza sativa)

General
- sacred symbol of fertility in the Orient; extremely important crop,
perhaps one of most important; domesticated in Asia (Thailand/Burma) around
7000 BC. Feeds more people than any other cereal.

There
are two sub-species of rice:

1. Oryza sativa var.
indica - Long grain.This
is dry, separates on cooking.Grown
in tropical and subtropical areas.The amylopectin content is greater than the amylose content.

2. Oryza sativa var. sativa - Japonica or short grain
rice.Soft and gluey texture
because of amylopectins and dextrose.More
temperate.

Cultivation.
Rice requires much water.Upland rice - wet but not standing water; Paddy rice - prefers
standing water. Most of
the world's rice is grown in paddies. Air chambers in the stem help to
move oxygen (air) to the roots that are embedded in the rather anaerobic
(oxygen-free) soils. An aquatic (floating) fern (Azolla) is
often cultivated with rice as a type of green manure. Azolla is
able to fix nitrogen and act as a natural fertilizer for the rice.
Traditionally, seedlings are individually planted in the paddies. In
the US, rice is usually seeded directly in the field, sometimes by airplane.